Circumference and Area of Circles

Front

What is the formula for the area of a circle?

Back

Area = πr², where r is the radius of the circle.

Front

How do you calculate the circumference of a circle?

Back

Circumference = πd, where d is the diameter of the circle.

Front

What is the relationship between diameter and radius?

Back

The radius is half of the diameter (r = d/2).

Front

If the diameter of a circle is 10 cm, what is the radius?

Back

The radius is 5 cm.

Front

What is the approximate value of π (pi)?

Back

π is approximately 3.14.

Front

How do you convert diameter to radius?

Back

Divide the diameter by 2.

Front

What is the circumference of a circle with a diameter of 14 cm?

Back

Circumference = πd = π(14) ≈ 43.98 cm.

Front

What does 'circumference' refer to in relation to a circle?

Back

Circumference is the distance around the circle.

Front

If the area of a circle is 78.5 cm², what is its radius?

Back

Radius can be found using the formula r = √(Area/π). For 78.5 cm², r ≈ 5 cm.

Front

What is the area of a circle with a radius of 7 cm?

Back

Area = πr² = π(7)² ≈ 153.94 cm².